Blade seal for rotary pump



Oct. 18, 1955 R. L. DILLS BLADE SEAL FOR ROTARY PUMP Filed Dec. 27, 195-1 Inventor-a Raymond L Dills,

His Attorneq.

United States Patent BLADE SEAL FOR ROTARY PUMP Raymond L. Dills, Erie, Pa., assignor to General Electric Company, a corporation of New York Application December 27, 1951, Serial No. 263,583 7 Claims. (Cl. 230-138) a stationary ring or annulus which is around the rotor.

In some types a round rotor revolves or rolls on an eccentric carried on a crankshaft inside a stationary concentric annulus. A blade arranged for being resiliently slidable in a slot in the annulus engages and follows the rotor as it travels around the inner periphery of the annulus. The refrigerant enters the annulus through an intake port on one side of and adjacent the blade. The rotor in revolving compresses the refrigerant and discharges it out an exhaust port on the other side of and adjacent the blade. In order for this type of compressor to operate efilciently, it is essential that an oil seal be maintained about the blade. Also, it is desirable that means he provided for equalizing the pressures between the high and low pressure sides of the compressor when the refrigerating unit becomes idle. This provision insures that the compressor is unloaded during the starting periods and thereby permits the employment of as small and economical a motor as possible for driving the compressor.

In View of the above, the primary object of my invention is to provide in a rotary type compressor including a blade, an improved arrangement for maintaining a satisfactory seal about the blade during the operating periods of the compressor.

Another object of my invention is to provide in an improved arrangement for maintaining a satisfactory seal about the blade of a rotary compressor during operating periods thereof, means for insuring rapid unloading of the compressor during idle periods thereof.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

in carrying out the objects of my invention I provide i a rotary compressor enclosed in a hermetically sealed case and comprising a ring or annulus, a rotor operating eccentrically in the annulus, and a blade arranged resiliently slidable in a radial slot in the annulus for engaging and following the rotor. 1 direct the gas and oil exhausted from the compressor both to a reservoir above the compressor and into an annular chamber formed about the compressor. In the reservoir the gas and oil are separated, the former passing into the case and the latter being directed to the radial slot for sealing the blade. The annular chamber includes an aperture for having the outer end of the blade fitted closely and slidably therein. This aperture permits some of the compressed gas and oil in the annular chamber to exit into the case whereby an oil seal is effected between the blade and the edges of the aperture. However, due to the close fit of the blade in the aperture, most of the gas is caused to sweep 2,721,026 Patented Oct. 18, 1955 over the portion of the blade in the radial slot whereby oil is deposited thereon for sealing. The aperture in the annular chamber also permits blowing of the seals about the blade from the high pressure case to the low pressure side or intake of the compressor when the refrigerating unit becomes idle.

For a better understanding of my invention, reference may be had to the accompanying drawing in which Fig. 1 is an elevational view of a refrigerating unit partly broken away to illustrate my invention incorporated therein; Fig. 2 is a section taken along the line 2-2 in Fig. 1; and Fig. 3 is a fragmentary sectional view illustrating the blade in its innermost position.

In Fig. l I have shown a refrigerating unit 1 which includes a hermetically sealed case 2. The case 2 houses in the upper part thereof a driving motor, which is not shown, and in the lower part a rotary compressor generally designated 3. The rotary compressor 3 includes an upper frame 4 and a lower frame 5 spaced apart by an annulus 6. A large cup 7 is fitted securely on a shoulder 8 formed on the lower portion of the upper frame 4 and encloses the 1 wer frame 5 and the annulus 6. As better seen in Fig. 2, the annulus 6 is located concentrically with respect to a vertical crankshaft 9. The crankshaft is suitably connected to the motor of the unit and portions of the crankshaft bear in both the upper frame 4 and the lower frame 5. Formed on the crankshaft 9 between the upper and lower frames and in substantially the same plane as the annulus 6 is an eccentric 10. A rotor 11 is carried rotatably on the eccentric and when the shaft 9 rotates the rotor operates eccentrically in the annulus 6.

Formed in the annulus 6 is a radial slot 12. The slot 12 is disposed between an intake port 13 and an exhaust port 14, also formed in the annulus 5. The intake port 13 has suitably connected thereto the end of a suction line 15 of a refrigerating system which is not shown. The exhaust port 14 exits into an annular exhaust chamber 16 formed by the lower frame 5 and the bottom portion of the cup 7. Positioned slidably in the radial slot 12 is a blade 17. The outer end of the blade 17 fits slidably in an aperture 18 formed in the side of the cup 7 and in substantial register with the slot 12. The tolerance between the blade 17 and the aperture 18 is very close, approximately .015. Carried securely on the outer side of the cup 7 at the aperture 18 is a bracket 19. A compression spring 20 seated in a bore 21 in the blade 17 engages the bracket 19 and in this manner the blade is arranged for following the surface of the rotor as it rotates eccentrically in the annulus 6 and thereby dividing the compressor into high and low pressure sides.

During operation of the unit a mixture of vaporous refrigerant and oil is taken into the annulus 6 through the intake port 13 from the suction line 15. Movement of the rotor causes the mixture of gas and oil to be compressed and expelled from the exhaust port 14 into the annular exhaust chamber 16. This exhaust mixture is indicated by 22 in Fig. 1. Connected to the chamber 16 is a conduit 23. The conduit 23 is formed to include a branch portion 24 and an upright end portion 25 whereby the flow of gas and oil passing through the conduit from the chamber 16 is divided into two paths. By means of the branch portion 24 one path is directed to the lower end or base of the crankshaft 9. The crankshaft 9 is formed to include a spiral groove 26 between the lower end thereof and the eccentric It The spiral groove 26 is effective for delivering gas and oil up and around the crankshaft 9 to the underside of the eccentric 10. A vertical groove 27 in the eccentric 10 permits the flow of gas and oil past the eccentric to another spiral groove 28 formed in the upper portion of the shaft 9 for delivery to the top of the frame 4. In this manner oil is deposited on the'shaft and rotor for lubricating purposes. Also, the vertical groove 27 in the eccentric equalizes pressure acrossthe eccentric. This prevents vertical movements of the shaft 9 due to pressure differences and thereby minimizes compressor noises. From the top of the upper frame 4 gas and oil are dumped into an annular reservoir 29 formed therein. In the reservoir 29 the gas and oil separate. 'The oil settles to the bottom of the reservoir and is indicated by 30 in Fig. l. The gaspasses from the reservoir and into thecase 2 through a plurality of passages 31 formed in the upper frame 4. From the case 2 the compressed gas is conducted to the rest of the system, which is not shown, through an exhaust line 32 connected to the bottom of the case.

'A passage 33 also formed in the upper frame 4 in the bottom of the reservoir 29 directs the oil 3% to the radial slot 12 whereby an oil seal is effected about the blade 17.

The end 25 of the conduit 23 is connected to the side of the cup 7 and thus directs the other path of gas and oil to a second annular chamber 34 formed about the compressor. By this arrangement the mixture of gas and oil in the chamber 34, which is indicated by 22a in Figs. 1

V and 2, is caused to sweep over the top, bottom and side surfaces of the blade 17 inwardly toward the intake port 13 for depositing oil films thereon and thereby assisting in sealing the blade. This arrangement also provides seal ing between the various other compressor elements such as between the annulus and the lower frame and the annulus and the upper frame.

past the portion of the blade in the aperture 18 whereby 7 an oil film is deposited on the edges of the aperture for sealing about the portion of the blade which moves reciprocatingly therein.

When the unit becomes idle the pressure in the case 2 or at the high pressure side of the compressor is greater than that in the suction line 15 or at the low pressure side of the compressor. As a result, the oil seals at the edges of the aperture 18 and about the portion of the blade 17 in the slot 12 are blown by the pressure in the case 2 into the intake port 13 and the suction line 15 for equalizing the pressures between the high and low pressure sides of the refrigerating unit and thereby unloading the compressor. The quantity of oil comprising these seals is small and unloading, therefore, occurs substantially immediately upon stopping.

When the unit restarts there is iusufiicient oil on the portion of the blade 17 in the slot 12 and the edges of a the aperture 18 to provide satisfactory compressor seals.

Consequently, during the first several starting revolutions of the compressor 3 it continues unloaded. In this manner the compressor is permitted to come up to operating speed. After the first several starting revolutions sealing about the blade and compressor is maintained in the manner above described and the compressor is again loaded.

While I have shown and described a specific embodiment of my invention, I do not desire my invention to be limited to the particular form shown and described and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigerating unit including a sealed case and a rotary compressor enclosed in said case and adapted for compressing a mixture of gas and oil, said rotary compressor including an annulus, a rotor operating eccentrically in said annulus, a radial slot in said annulus, and a with said case, said aperture having the outer end of said blade fitted closely and slidably therein, and means for conducting gas and oil exhausted from said compressor to said chamber, said gas and oil sweeping over the portions of said blade in said radial slot and in said aperture thereby to provide oil seals thereon, saidoil seals being blown by pressure in said case into said low pressure side of said compressor when said compressor becomes idle whereby the pressures between said high and low pressure sides are equalized for unloading said compressor.

2. In a refrigerating unit including a sealed case and a rotary compressor enclosed in said case and adapted for compressing a mixture of gas and oil, said rotary compressor including an annulus, a rotor operating eccentrically in said annulus, a radial slot in said annulus, and a blade in said slot following said rotor and thereby dividing said compressor into high and low pressure sides, means for maintaining an oil seal about said blade during operating periods of said unit and unloading said compressor during idle periods thereof comprising; an annular chamber formed about said compressor, said annular chamber including an aperture providing communication with said case and being in substantial register with said radial slot, said aperture having the outer end of said blade fitted closely and slidably therein, and means for conducting gas and oil exhausted from said compressor to said chamber, said gas and oil sweeping over the portionsof said blade in said radial slot and in said aperture thereby to provide the oil seals thereon, said oil seals being blown by pressure in said case into said low pressure side of said compressor when said compressor becomes idle whereby the pressures between said high and low pressure sides are equalized for unloading said compressor.

3. In a refrigerating unit including a sealed case and a rotary compressor enclosed in said case and adapted for compressing a mixture of gas and oil, said rotary compressor including an annulus, a rotor operating eccentrically in said annulus, a radial slot in said annulus, and a blade in said slot following said rotor and thereby dividing said compressor into high and low pressure sides, means for maintaining an oil seal at said blade during operating periods of said unit and unloading said compressor during idle periods thereof comprising; a reservoir, means for conducting gas and oil exhausted from said compressor to said reservoir for separation therein, means for directing oil from said reservoir to said radial slot for sealing said blade, means for conducting gas from said reservoir to said case, a chamber formed about the outer end of said radial slot, said chamber including an aperture providing communication with said case, said aperture having the outer end of said blade fitted closely and slidably therein, and means for conducting gas and oil exhausted from said compressor to said chamber, said gas and oil sweeping over the portion of said blade in said radial slot thereby to deposit an oil film thereon for assisting in maintaining 'an oil seal about said blade, said gas and oil sweeping past the portion of said blade in said aperture thereby to provide an oil seal thereon, said oil seals being blown by pressure insaid case into said low pressure side of said compressor when said compressor becomes idle wherebythe pressures between said high and lower pressure sides are equalized for unloading said compressor. 7

4. In a refrigerating unit including a sealed case and a rotary compressor enclosed in said case and adapted for compressing a mixture of gas and oil, said rotary compressor including an annulus, a rotor operating eccentrically in said annulus, a radial slot in said annulus, and a blade in said slot following said rotor and thereby dividing said compressor into high and low pressure sides, means for maintaining an oil seal about said blade during operating periods of said unit and unloading said compressor during idle periods thereof comprising; a reservoir, means for conducting gas and oil exhausted from said compressor to said reservoir for separation therein, means for directing oil from said reservoir to said radial slot for sealing said blade, means for conducting gas from said reservoir to said case, an annular chamber formed about said compressor, said annular chamber including an aperture providing communication with said case and being in substantial register with said radial slot in said annulus, said aperture having the outer end of said blade fitted closely and slidably therein, and means for conducting gas and oil exhausted from said compressor to said chamber, said gas and oil sweeping over the portion of said blade in said radial slot thereby to deposit an oil film thereon for assisting in maintaining an oil seal about said blade, said gas sweeping past the portion of said blade in said aperture to provide an oil seal thereon, said oil seals being blown by pressure in said case into said low pressure side of said compressor when said compressor becomes idle whereby the pressures between said high and low pressure sides are equalized for unloading said compressor.

5. In a refrigerating unit including a sealed case and a rotary compressor enclosed in said case and adapted for compressing a mixture of gas and oil, said rotary compressor including an annulus, a crankshaft having an eccentric formed thereon, a rotor carried on said eccentric and operating in said annulus, a radial slot in said annulus, and a blade in said slot following said rotor and thereby dividing said compressor into high and low pressure sides, means for maintaining an oil seal about said blade during operating periods of said unit and unloading said compressor during idle periods thereof comprising; a reservoir, a spiral groove formed in said crankshaft and communicating with said reservoir, means conducting gas and oil exhausted from said compressor to said spiral groove whereby said gas and oil are delivered to said reservoir for separation therein, means for directing oil from said reservoir to said radial slot for sealing said blade, means for conducting gas from said reservoir to said case, a chamber formed about the outer end of said radial slot, said chamber including an aperture providing communication with said case, said aperture having the outer end of said blade fitted closely and slidably therein, and means conducting gas and oil exhausted from said compressor to said chamber, said gas and oil sweeping over the portion of said blade in said radial slot thereby to deposit an oil film thereon for assisting in maintaining an oil seal about said blade, said gas and oil sweeping past the portion of said blade in said aperture to provide an oil seal thereon, said oil seals being blown by pressure in said case into said low pressure side of said compressor when said compressor becomes idle whereby the pressures between said high and low pressure sides are equalized for unloading said compressor.

6. In a refrigerating unit including a sealed case and a rotary compressor enclosed in said case and adapted for compressing a mixture of gas and oil, said rotary compressor including an annulus, a crankshaft having an eccentric formed thereon, a rotor carried on said eccentric and operating in said annulus, a radial slot in said annulus, and a blade in said slot following said rotor and thereby dividing said compressor into high and low pressure sides, means for maintaining an oil seal about said blade during operating periods of said unit and unloading said compressor during idle periods thereof comprising; a reservoir, a spiral groove formed in said crankshaft and communicating with said reservoir, means for conducting gas and oil exhausted from said compressor to said spiral groove whereby said gas and oil are delivered to said reservoir for separation therein, means for directing oil from said reservoir to said slot for providing an oil seal about said blade, means for conducting gas from said reservoir to said case, an annular chamber formed about said compressor, said annular chamber including an aperture providing communication with said case and being in substantial register with said radial slot in said annulus, said aperture having the outer end of said blade fitted closely and slidably therein, and means for conducting gas and oil exhausted from said compressor to said annular chamber, said gas and oil sweeping over the portion of said blade in said radial slot thereby to deposit an oil film thereon for assisting in maintaining an oil seal about said blade, said gas and oil sweeping past the portion of said blade in said aperture to provide an oil seal thereon, said oil seals being blown by pressure in said case into said low pressure side of said compressor when said compressor becomes idle whereby the pressures between said high and low pressure sides are equalized for unloading said compressor.

7. In a refrigerating unit including a sealed case and a rotary compressor enclosed in said case and adapted for compressing a mixture of gas and oil, said rotary compressor including an upper frame, a lower frame, an annulus between said upper frame and said lower frame, a crankshaft having an eccentric formed thereon, a rotor carried on said eccentric and operating in said annulus, a radial slot in said annulus, and a blade in said radial slot following said rotor and thereby dividing said compressor into high and low pressure sides, means for maintaining an oil seal about said blade during operating periods of said unit and unloading said compressor during idle periods thereof comprising; an exhaust chamber receiving a mixture of gas and oil exhausted from said compressor, means for dividing said mixture of gas and oil discharged from said exhaust chamber into two paths, a reservoir formed in said upper frame, a spiral groove formed in said crankshaft and communicating with said reservoir, one of said paths being directed to said spiral groove whereby gas and oil are delivered to said reservoir for separation therein, means providing communication between said reservoir and said radial slot whereby oil is directed to said slot for providing a seal about said blade, means providing communication between said reservoir and said case for conducting gas from said reservoir to said case, an annular chamber formed about said compressor, said annular chamber including an aperture providing communication with said case and being in substantial register with said radial slot in said annulus, said aperture havng the outer end of said blade fitted closely and slidably therein, the other of said paths being directed to said annular chamber, said gas and oil sweeping over the portion of said blade in said radial passage thereby to deposit an oil film thereon for assisting in maintaining an oil seal about said blade, said gas and oil sweeping past the portion of said blade in said aperture for maintaining an oil seal thereon, and said gas depositing oil on the surfaces between said annulus and said upper and lower frames for sealing, said oil seals on said portions of said blade in said slot and in said aperture being blown by pressure in said case into said low pressure side of said compressor when said compressor becomes idle whereby the pressures between said high and said low pressure sides are equalized for unloading said compressor.

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